Sound signal



June 11, 1929. R. M. CRI' ICHFIELD 1.716.36

SOUND SIGNAL Filed Sept. 23, 1927 Patented June 11, 1929.

warren stares rarest" orricr.

ROBERT M. CRITGHFIELD, OF ANDERSON, INDIANA, ASSIGNOR TO DEIiCO-REIVIY 001t- PORATION, OF DAYTON, CHIC, A CORPORATION 013 DELAWARE.

SOUND SIGNAL.

Application filed September 23, 1927. Serial No. 221,474.

This invention relates to sound signals and more particularly to the type of signal comprising a diaphragm which is vibrated by mechanism operated by a rotating shaft.

It is one of the objects of the present invention to improve the quality of tone produced by the sound signal or horn, by min1- mizin g the transmission to the diaphragm of noises due to the operation of the mechanism which vibrates the diaphragm.

In the present invention this object is accomplished by transmitting motion from the rotary drive shaft through a pneumat c fluid pressure device to the diaphragm, this device serving to absorb mechanical noises which would otherwise be transmitted to the diaphragm and amplified by the projector.

Further objects and advantages of the present invention will be apparent from the following description, reference being bad to the accompanying drawings, wherein a preferred form of embodiment of the present invention is clearly shown.

In the drawings:

Fig. 1 is a transverse sectional view of an electrically operated horn embodying the present invention.

Fig. 2 is a fragmentary sectional view on the line 22 of Fig. 1.

Fig. 3 is a sectional view on the line 33 of Fig. 1.

A frame 20 is attached by screws 21 to a bracket 22 supporting a U-shaped motor frame 23 which provides pole pieces 24 and 25, and which is energized by a field magnet coil 26. The frame 23 provides a bearing.

27 and the bracket 22 a bearing 28 for supporting the shaft 29 of an armature 30.

The shaft 29 operates a cam or ratchet 31,

the teeth of which are adapted to engage a wear piece 32 provided by rod 33 which is,

slidable through a bushing 3st attached to the web 35 of the frame 20. A spring 36 is maintained by an adjustable screw 37 against the end of the shaft 29 for the purpose of urging the shaft 29 toward the right so that the ratchet 31 will be maintained in engagement with the wear piece 32. Motion of the wear piece 32 toward the right is-resisted by a spring 40 bearing against the bushing 34 and against a washer 41 surrounding the rod 33 and retained by a spring clip 42 which is snapped into a groove 43 provided by the rod 33. It is therefore obvious that rotation of the motor shaft 29 will eflect reciprocation of the rod 33.

The sound producing mechanism of the horn comprises a diaphragm 50. which is clamped between a. collar 51 and the frame 20 by a number of screws 52. The collar 51 carries a projector 53.

Motion is transmitted from the reciproeating rod 33 to the diaphragm by means including a pneumatic or fluid pressure device. This device comprises a piston 54 carried by the rod 33 and cooperating with a relatively shallow cylinder 55 which is attached to the diaphragm by screws 56 which pass through the diaphragm and threadedly engage a reinforcing plate 57. The cylinder end wall is provided with an aperture 58 for receiving the rod 33 and a stuffing box is provided for the rod- 33 by a felt disc 59 which is retained by a cup-shaped member 60. The member 60 is provided with an aperture 61 for receiving the rod 33 and with a flange 62 through which a number of screws 63 pass for the purpose of securing the member 60 to the end wall of the cylinder 55.

When the rod 33 is moved toward the right as the result of the engagement of the teeth of the ratchet 31 with the wear piece 32, the air which occupies the space between the diaphragm 50 and the piston 54 will be compressed and the air at the left of the piston will be somewhat rarefied. This condition will cause the diaphragm to move toward the projector. When the rod 33 moves toward the left due to the action of the spring 40, the air between the piston and the end wall of the cylinder 55 will be compressed and the air at the right of the piston will be rarefied. Hence the diaphragm will move toward the left. In this way the motion from the reciprocating rod is transmitted to the diaphragm pneumatically in either direction. The noise produced by the ratchet 31 striking the wear piece 32 is not appreciably transmitted to the diaphragm. Therefore,the sound pro duced by the horn will besubstantially only that produced by the vibration of the diaphragm unaffected by the noise making vibrations produced by the parts to transmit motion to the diaphragm.

While the form of embodiment of the present invention as herein disclosed, c0n stitutes a preferred form, it is to be understood that other forms might be adopted,

all coming within the scope of the claims which follow.

What is claimed is as follows:

1. A sound signal comprising in combination, a diaphragm, a reciprocating member, means for operating the reciprocating memher, and fluid pressure means for transmitting the motion of the reciprocating member to the diaphragm.

2. A sound signal comprising in combina- I tion, a diaphragm, a reciprocating member, means for operating the reciprocating memher, and piston and cylinder members one of which is attached to the diaphragm and the other to the reciprocating member for the purpose of transmitting the motion of the reciprocatingniember to the diaphragm through air trapped between the piston and the cylinder.

3. A sound signal according to claim 2 in which the cylinder member is carried by the diaphragm and the piston member is pro- Vided by the reciprocating member.

4. A sound signal comprising in combination, a diaphragm, a rod mounted to reciprocate at right angle to the plane of the diaphragm, a rotary ratchet engageable with one end of the rod for moving the rod in one direction, a spring for urging the rod toward the ratchet, and piston and cylinder members one of which is attached to the diaphragm and the other to the rod for the purpose of transmitting the motion of the rod to the diaphragm through air trapped between the piston and cylinder.

In testimony whereof 1 hereto ailix my signature.

ROBERT M. CRITCHFIELD. 

